The present invention is related to an ID (identification) transfer method for wireless communication appliances, used to establish a wireless communication between appliances having the same IDs.
Generally speaking, in an ID transfer method of wireless communication appliances where a wireless communication is established between wireless communication appliances having the same IDs, such an ID capable of recognizing these relevant wireless communication appliances is inserted into the protocol of a message used therein. In this case, the bit number of the ID must be increased so as to avoid erroneous recognitions. If the bit number of the ID is increased, then the message itself is extended, or prolonged. When the message is extended, the protocol time of this message is prolonged. As a result, the following problems will occur:
1) A battery lifetime is shortened in a battery-built-in type wireless appliance such as a cordless type telephone unit. PA1 2) Time required to establish a wireless connection is prolonged. PA1 3) Since a message itself is extended, there are many cases that this message receives radio interference noise.
FIG. 1 schematically shows the format of the wireless message presently used in various wireless appliances such as cordless type telephone units.
In FIG. 1, reference numerals 1, 2, 3 to 6 indicate the respective digits for constituting a wireless message, and each digit is constructed of 4 bits. That is, reference numeral 1 shows a bit sync (synchronization) signal (Bit Sync) constituted by a continuation of mark signals. The bit sync signal 1 is used for waiting purposes when a message is started to be transmitted, and when a message is started to be received. This bit sync signal 1 is added to a head of a message. Reference numeral 2 shows a frame sync signal (Frame Sync) constituted by fixed data in which a mark signal is mixed with a space signal. This frame sync signal 2 is used to indicate a head of data. Reference numeral 3 indicates an ID code constituted by 3-digit IDs "ID0" to "ID2". These ID codes "ID0", "ID1", and "ID2" correspond to code signals for pairing wireless appliances which communicate with each other, for example, a mother unit and a child unit in a cordless telephone system. Messages having different ID codes are neglected between wireless appliances.
Reference numeral 4 shows a command signal for indicating a content of a message to be executed. For example, as this command signal 4, the following commands are provided:
Ringing request/acknowledge command: Ring REQ/ACK, PA0 Ringing command: Ring RUN, PA0 Outer line request/acknowledge command: Outer line REQ/ACK, PA0 Execution command for connecting outer line: Outer line RUN, PA0 Dialing request/acknowledge command: Dial REQ/ACK, PA0 Dialing execution command: Dial RUN.
Reference numeral 5 is data for indicating detailed contents of the command signal. For instance, in the case of the command "Dial REQ", a content of dialing is entered into the data. In the case of the command "Ring REQ", ON/OFF is entered into the data. Reference numeral 6 shows a check sum which is used to check an error that may have occurred in a receiver side. To this check sum, a total of lower 4 bits of the data 3, 4, 5 are entered.
FIG. 2 schematically illustrates a sequential operation when a message is executed. For instance, in order that a telephone call issued from an outer line is transferred to a child unit, it is required to ring this child. To this end, the command signal "Ring REQ" is first sent from a mother unit to the child unit. When this command signal is recognized by the child unit, the command signal "Ring ACK" is returned from the child unit to the mother unit. When the mother unit receives the command signal "Ring ACK" issued from the child, the mother unit sends the command signal "Ring RUN" to the child unit. When this command signal "Ring RUN" is received by the child unit, the message is executed.
In other words, after the message as shown in FIG. 1 has been sent/received one and a half return times, the message is executed. In this case, when the mother unit can not receive "ACK" issued from the child unit within a preselected time period after having sent out "REQ", this mother unit judges that the child unit does not receive "REQ". Also, when RUN is not returned from the mother unit within a preselected time period after the child unit has sent "ACK" to the mother unit, the child unit invalidates "REQ". As described above, in the case that the mother unit receives "ACK" and the child unit receives "RUN" between the mother unit and the child unit, both the mother/child units wait for such a message having a definite content.
Generally speaking, since the 10-bit ID is conventionally and widely used in wireless appliances such as cordless type telephone units, a 3-digit (1 digit=4 bits) ID code may be sufficiently provided. Very recently, IDs made of larger bit numbers than 10 bits, for instance, 16 bits are utilized, so that the 3-digit ID code represents shortage of the bit number.
To increase a bit number of an ID, a length of a message may be extended. However, when the length of the message is extended, protocol time of the message is prolonged. As a result, since a time period required to establish a wireless communication connection between relevant wireless appliances is prolonged, there are problems that a battery lifetime of such a wireless appliance as a battery-built-in type cordless telephone is shortened, and the wireless communication is susceptible to radio interference noise.